Which of the following statement regarding the response of living organisms to external stimuli is correct ?

Options

A. The external environmental stimuli can be physical, chemical or biological.
B. All organisms, from the prokaryotes to the most complex eukaryotes can sense and respond to environmental stimuli.
C. Consciousness and response to external stimuli is the defining property of living organisms.
D. All of these

Explanation

To determine which statement regarding the response of living organisms to external stimuli is correct, we can analyze the provided options step by step.

### Step 1: Understanding the Concept of Stimuli
- Living organisms have the ability to sense changes in their environment, known as stimuli. These stimuli can be physical (like temperature), chemical (like pH changes), or biological (like hormonal changes).

**Hint:** Look for the types of stimuli that organisms can respond to.

### Step 2: Evaluating the First Statement
- The first statement claims that external environmental stimuli can be physical, chemical, or biological. This is true, as we just defined these types of stimuli.

**Hint:** Confirm if the types of stimuli mentioned are indeed recognized in biology.

### Step 3: Evaluating the Second Statement
- The second statement asserts that all organisms, from prokaryotes to complex eukaryotes, can sense and respond to environmental stimuli. This is also correct, as all living organisms exhibit this property.

**Hint:** Consider whether all forms of life, regardless of complexity, have this ability.

### Step 4: Evaluating the Third Statement
- The third statement indicates that consciousness and response to external stimuli is a defining property of living organisms. This is indeed correct, as this ability distinguishes living organisms from non-living entities.

**Hint:** Think about what characteristics define living organisms compared to non-living things.

### Step 5: Conclusion
- Since all three statements are correct, the final answer is that all of these statements regarding the response of living organisms to external stimuli are accurate.

**Final Answer:** All of these (Option 4).